Note 3 - Stocked-based Compensation - Stock Option Activity (Details) - $ / shares	6 Months Ended
	Jun. 30, 2022
Options outstanding, options (in shares)	427,580
Options outstanding (in dollars per share)	$ 3.50
Granted to employees and non-employee directors, options (in shares)	0
Granted to employees and non-employee directors (in dollars per share)	$ 0
Exercised, options (in shares)	(8,332)
Exercised (in dollars per share)	$ 3.62
Canceled/expired/forfeited, options (in shares)	0
Canceled/expired/forfeited (in dollars per share)	$ 0
Options outstanding, options (in shares)	419,248
Options outstanding (in dollars per share)	$ 3.50
Options exercisable, options (in shares)	404,248
Options exercisable (in dollars per share)	$ 3.50